QM5 cells, set up 1 to 2 days previously in 25‐cm2 flasks (see appendix 4G), and 95‐98% confluent.

Complete 1× M199 medium, prewarmed to 37°C (see recipe)

Penicillin‐streptomycin (see recipe)

Amphotericin B (see recipe)

Small rubber bulb for Pasteur pipet

Disposable, cotton‐plugged, glass Pasteur pipets, sterile

1‐dram (dm) or 2‐dm glass vials, sterile

5‐ml serologic pipets, sterile

15‐ml conical tube, sterile

2‐ml cryovials

NOTE: A confluent monolayer is considered to be ≥95% confluent without being over confluent unless otherwise stated (see appendix 4G and Fig. for further details on cellular confluency).NOTE: A separate flask will be required for each picked plaque. The following protocol describes manipulation of each picked plaque;
repeat for each picked plaque.